Title 16 - Buildings and Construction

16.310 Residential Code

16.310.N1105.2

Section N1105.2 of the 2024 International Residential Code is hereby amended to read as follows:

N1105.2 Simulated building performance compliance. Compliance based on simulated building performance requires that a building comply with the following:

1.

The requirements of the sections indicated within Table N1105.2.
2.

The proposed total building thermal envelope thermal conductance (TC) shall be less than or equal to the required total building thermal envelope TC using the prescriptive U-factors and F-factors from Table N1102.1.2 multiplied by 1.08 in Climate Zones 0, 1 and 2, and 1.15 in Climate Zones 3 through 8, in accordance with Equation 11-6 and Section N1102.1.5. The area-weighted maximum fenestration SHGC permitted in Climate Zones 0 through 3 shall be 0.30.

Equation 11-6 For Climate Zones 0–2: TC_{Proposed design} ≤ 1.08 × TC_{Prescriptive reference design}

For Climate Zones 3–8: TC_{Proposed design} ≤ 1.15 × TC_{Prescriptive reference design}

3.

For all dwelling units, the annual energy cost of the proposed design shall be less than or equal to 85 percent of the annual energy cost of the standard reference design. For each dwelling unit with greater than 5,000 square feet (465 m2) of living space located above grade plane, the annual energy cost of the dwelling unit shall be reduced by an additional 5 percent of annual energy cost of the standard reference design. Energy prices shall be taken from an approved source, such as the US Energy Information Administration’s State Energy Data System prices and expenditures reports. Code officials shall be permitted to require time-of-use pricing in energy cost calculations.

Exceptions:

1.

The energy use based on source energy expressed in Btu or Btu per square foot of conditioned floor area shall be permitted to be substituted for the energy cost. The source energy multiplier for electricity shall be 2.51. The source energy multipliers shall be 1.09 for natural gas, 1.15 for propane, 1.19 for fuel oil, and 1.30 for imported liquified natural gas.
2.

The energy use based on site energy expressed in Btu or Btu per square foot of conditioned floor area shall be permitted to be substituted for the energy cost.

(History: Ord. No. BC-3513, 41, 2026)

Effective on: 1/1/1901